From an older thread: "Turn off the Oregon, press and hold the upper left corner of the screen and power the unit on. You will eventually be asked if you want to reset user data. If you answer "Yes" the unit will be master reset."

From an older thread: "Turn off the Oregon, press and hold the upper left corner of the screen and power the unit on. You will eventually be asked if you want to reset user data. If you answer "Yes" the unit will be master reset."